1. Field of the Invention
This invention relates generally to stacking and unstacking devices and, more particularly, to a device for stacking and unstacking baking pans using a gripper assembly.
2. Description of the Prior Art
In the baking industry, empty baking pans are generally stored in single stacks on movable pan trucks or at designated locations on the floor of the bakery. The baking pans are typically rectangular and have a number of individual baking forms located in the pan. A stacker machine stacks the pans in a single, vertical stack. This stack can then be transported to a new location near the oven by moving the pan truck on which the pans are stacked or by a conventional automatic storage and retrieval system. At the new location, a separate unstacker machine unstacks the stacked pans, one at a time. The unstacker machine picks up the top pan from the stack of pans and transports this pan onto a conveyor leading to the bakery processing system. As the pan moves through the bakery processing system, the material to be baked is introduced into the pan and the filed pan is moved to the oven for baking. When baking is completed, the baking pan is typically moved from the oven by a conveyor and another stacker machine removes the baking pans one at a time from the conveyor and stacks the pans in a single column.
These single stack stacker and unstacker machines have certain disadvantages. For example, these machines generally stack or unstack the baking pans in a single, vertical stack or column. Further, these machines must be preset by an operator for a particular pan size and must be reset if the pan size used in the baking process changes. Additionally, these known stacker and unstacker machines typically use a magnetic pick-up device to magnetically lift the top pan of the stack and transport it to its destination. These magnetic pick-up devices can damage the baking surface of the pan. Further, these magnetic pick-up devices are prone to picking up two or more pans, particularly if the adjacent upper pans happen to be stuck together. In addition, since only a single stack of pans is transported to or from a particular location, the stacker and unstacker machines must operate at a relatively high speed in order to continually move the necessary number of pans, one at a time, to or from the designated stack. This greatly increases the wear and tear on the stacker and unstacker machines.
Therefore, it is an object of the present invention to provide a device for stacking and unstacking a plurality of pans, each from a separate pan stack. It is a further object of the invention to provide a device which picks up the pans without damaging the baking surface of the pans and which easily adapts for use with a wide variety of pan sizes. It is also an object of the invention to provide a bakery processing system utilizing the stacking and unstacking device of the present invention to provide for smooth and efficient pan stacking, unstacking and transport in the bakery processing system.